CARTILAGES OF THE LARYNX 515 
CARTILAGES OF THE LARYNX 
There are three single cartilages and one pair; the single cartilages are the 
ericoid, thyroid, and epiglottic; the arytenoid cartilages are paired. 
The cricoid cartilage (Cartilago cricoidea) is shaped like a signet ring. The 
dorsal part is a broad, thick, quadrilateral plate termed the lamina; the external 
(dorsal) surface of this is marked by a median ridge (Crista mediana) separating two 
shallow cavities, from which the dorsal crico-arytenoid muscles arise. On either 
side of these depressions are two articular facets. The anterior facet (Facies articu- 
laris aryteenoidea) is at the anterior border, is oval and convex, and articulates 
with the arytenoid cartilage. The posterior facet (Facies articularis thyreoidea) is 
situated on the front of a ridge, a short distance from the posterior border; it is 
concave, and articulates with the posterior cornu of the thyroid cartilage. The 
ventral and lateral parts of the ring are formed by a curved band, called the arch 
(Arcus), which is narrowest ventrally. The lateral surfaces of the arch are grooved 
Thyroid 
~- fissure — Lateral border 
=~ 
\ . 
Crico-tracheal \ Oblique 
membrane \ line . 
Vey :, . . 
Crico-thyroid Laryngeal prominence 
membrane 
Fie. 457 —LarYNGEAL CaRTILAGES AND Part oF TRACHEA OF Horse; RicuT VIEw. 
For “thyroid wing”’ read ‘‘thyroid lamina.” 
for the crico-thyroid muscle. The anterior border of the lamina is thick and 
slightly concave; the posterior border is thin and irregular. The anterior border 
of the arch is concave ventrally and gives attachment to the crico-thyroid membrane; 
laterally it is thicker and gives attachment to the crico-arytenoideus lateralis 
muscle. The posterior border of the cartilage is attached to the first ring of the 
trachea by the crico-tracheal membrane. The internal surface is smooth and is 
covered with mucous membrane. 
The thyroid cartilage (Cartilago thyreoidea) consists of a median thickened 
portion, termed the body, and two lateral lamine. The body forms ventrally a 
slight prominence (Prominentia laryngea), which can be felt, but is not visible in 
the living subject; it is related dorsally to the base of the epiglottis, which is at- 
tached to it by an elastic igament. The lamine or wings spring from the body 
on either side and form a large part of the lateral wall of the larynx. Each is a 
rhomboid plate, presenting a slightly convex lateral surface, which is divided into 
two areas by an oblique line (Linea obliqua), on which the thyro-hyoid and thyro- 
pharyngeus muscles meet. The dorsal border is nearly straight; it gives attach- 
ment to the pharyngeal fascia and the palato-pharyngeus muscle, and bears a cornu 
ateachend. The anterior cornu (Cornu orale) articulates with the cartilage of the 
